[polly] [clang] [clang-format] Add AllowShortType and ExceptShortType options for AlwaysBreakAfterReturnType. (PR #78011)

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rmarker wrote:

> +1. In addition, we should deprecate `None` (in documentation only) and rename `AllowShortType` to `Automatic`, followed by `ExceptShortType` which means "`Automatic` except for short return types". Then IMO `ExceptShortType` is unambiguous. If you still think `NeverShortType` is clearer, I would change it to `NotShortType`.

Sounds like a plan.
Updated PR with changes.

https://github.com/llvm/llvm-project/pull/78011